1. Field of the Invention
The present invention relates to physical exercise machines and devices. More particularly, the invention relates to an electronically controlled force production and force control mechanism and methodology for use with numerous types of exercise machines.
The skeletal-muscular system of the human body consists of the 206 bones and over 650 muscles that maintain the skeletal structure, protect and support the internal organs, and help the body move. During recent years there has been a great deal of interest shown in the regular and systematic exercise of important body muscles for the development of specific strengths and physical abilities, for the development of desired body shapes and proportions, and for the general maintenance of body health. Particular attention has been devoted to the development of the chest muscles (pectoralis major), back muscles (trapezius), upper arm muscles (biceps and triceps) and principal leg muscles (quadriceps femoris) through weight lifting and force application and resistance exercise programs and machines. Amateur and professional athletes and body builders, both male and female alike, spend many hours per week in such exercise programs utilizing a broad range of apparatus from simple barbells to complex and sophisticated exercise machines.
2. Prior Art
Conventional Exercise Machines. Past and present resistance or force type exercise machines typically utilize the force of gravity acting on a stack of weights to apply a resistance force to the movement of a body part to strengthen the muscles controlling such part. The machine user selects the number of weights desired for stressing the muscles involved in the movement of the body part in question. Alternatively, weights may be supported at variable distances along a force beam whereby the resistance force applied to the user's body part is increased by the distance at which the weight is positioned from the pivot point of the force beam. Also, resistance to movement force is often varied during certain ranges of the exercise motion by utilizing a cam to vary the effective weight of a weight stack or the length of a force moment arm of the device.
The greatest deficiencies of the present exercise machines are that they are subject to the effects of gravity, friction and inertia. The combination of these three forces causes the actual user-experienced force to be less than predictable except within very limited performance parameters. None of the present day exercise machines have the ability to substantially increase or decrease the selected applied force other than by the slight variation caused by the changing leverages resulting from changes in the position of a cam. None offers an accurate predictable force at varied exercise speeds of rates and none have the ability to offer a corresponding increase in resistance for the negative (eccentric contraction) stroke or motion when the exercised muscles are lengthening compared to the positive (concentric contraction) stroke or motion when the exercised muscles are shortening.
Electronic Art. Recently, several electronically controlled exercise machines have been introduced to the body exercise machine market. Their forces are created by: a) an electromagnetic braking system; b) a hydraulic force system; c) a pneumatics force system; or a D.C. motor used as a dynamic brake.
The electromagnetic braking systems offer "concentric only" resistance. This type of exercise machine targets the weakest force generated by a muscle and consequently the results from the exercise machine are limited to the low force concentric contraction (shortening) of the muscles. As a result, the maximum "overload tension" force available through controlled utilization of high eccentric contractions is not allowed. This limitation also prevents any positive result from the exercise movement other than from the concentric motion or stroke and therefore is a technological regression.
The air hydraulics or pneumatics system and the fluid hydraulics system of applying resistance forces in exercise machines have been utilized by several manufacturers. These machines allow performance of both eccentric and concentric force contractions. They utilize air or fluid pressure and mechanical linkages or leverage systems to provide the resistance forces against which exercise forces are applied by the user. Both systems are quite expensive to produce and their overall speed and force potential are not seen to be controllable to the extent of the mechanism of the present invention. Further, these systems are often large and bulky and they have a potential for fluid leaks, having bubbles in their fluid channels, and they require systematic maintenance to assure correct operation.
The D.C. motor has recently been utilized as a dynamic braking device in exercise machines. This method of producing a resistance force is rather basic and in its present state is not easily adaptable to even simple force curves. Further, exercise machines with dynamic braking devices have a problem with inertia and thereby may be less safe in their operation. Inertia also reduces response time to electronic commands from the control system and consequently reduces the performance envelope of the mechanism.